Photographic pressure-printing frame.



J. &'H. PRITCHARD. 'PHOTOGRAPEIG PRESSURE PRINTING FRAME.

APPLIOATIONTILED FEB. l2, 1908.

Patented May 4, 1909.

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`over the sai(Y valve.

marren :PHOTO GRA?H3IC PRE SS'UIRE -PRINTING FRA-AELE im. asoma.

Application led. Eeuruary 12, 1908.

specificati@ of Letters Patent.

Patented May 4'-, 1909. Serial No. 415,416-2.

To all whom it may coi/teem.'

-King of Great Britain, and both' residents of l Roseber,Y avenue, London, E. C., England, scienti e-instrument-case makers, have invented certain'neiv and useful improvements in .Photographic Pressure-Printing F rames, of which the following is a specification. V

Our invention relates to printing frames of the kind in which equal distribution of pressure is obtained by exhausting air from between the front plate of the frame, and the movable .back plate.

The object of the present invention is to obtain an improved printing frame'of this class and to this end an automatic air eX- haust valve is provided controlling an aperture in the back plate and cooperating with a pump to be laced directly on the back plate Packing means are provided for obtaining an air tight closure between the open end of the pump and the back plate. ln this arrangement, the pump is directly brought on the back plate of the printing frame to be exhausted, and after exhausting the air from one frame the pump can be easily transferred to another frame.

In tlie accompanying drawings, lfigure l is a rear vier.Y of the in'xproved pressure l'raine, parts being broken :may to shofv the construction. Figs. 2 and 3 are sections on lines 2-`2 and 3-3 respectively of Fig. l.

The pressure frame of our invention comprises the usual plateglass iront A mounted 1n a frame B having a rearwardly extending marginal eoaming or llange forming a guide for the back or presser plate (I, beta een which and the glass front A, thel negative l) and the metal vplate E to be etched are received and pressed together.

'lille back or presser plate C is preferably of plate-glass. or equivalent hard yet resilient material, and in suclr case is mounted in a lramc l? adapted to lit easily but with Sullicient accuracy vwithin the coaming l). The l'ramc lll may be provided with a pair of handles]lby means ol which it may be manipulated, these handles serving also' for manipulating the entire pressure frame when ready for work.

The hack or presser plate (l may be laced with a layer c oi l'elt or other l'abric adapted t0 constitute a slightly yielding bed for the i metal plate E, and thus obviate the risk of the glass plate C being fractured by the pou'- erful pressure exerted. n

Between the iront late A and back plate C an air-tight chamer G- is formed, this chamber being laterally bound around its j entire circuit by means of a gasket H of soft indiarubber interposed between the plates A and C outside the margin of the negative D and metal plate E and layer of felt This l air chamber G communicates with an aperture j in the back plate @provided with a valve J throughwhich the air in the chamber l l is exhausted by means of der to cause the plates A l together by atmospheric pressure, channels such as g being preferably provided in vthe felt or other backing c for the purpose of affording ready access, from the space immediately uithin the gasket H, to the aperture y'. l The valve J is preferably constituted by l an outwardly opening V-shaped llap cut ina l thick disk 7c of indiarubber, leather, or equivan air-pump in'or`4 and C to be forced alent material cemented to the outer surface of the back plate C, the aperture y' being situated near the root of the lla so as to ob` viate as lar as possible the risli of disturbanceof the valve and consequent leakage of air from outside into the chamber G when the latter has been exhausted. may be ol' sulhcient area to l l'or the air The disk c provide a seating pump employed to exhaust the l chamber g, or said seating may, as shown, be l constituted by a separate rin or gasketvK ol' indiarubber, leat ier or the ike encircling l the disk l' and cemented to the outer surface ol' the plate (l. The ring or gasket li is made of such dil ameter as 'to form a seating lor the mouth l l of the cylinder L, so that when the latter is applied over the valve J' and the Crank-han i die Q rotated, to retract the piston M, the air within the chamber G will be exhausted l through the valve J into the cylinder, after I which the air-pump may be removed from |-the pressure frame and used l'or exhausting I a second oranynumber ol' such frames in succession. f l When it is required to open the pressure l lrame, it is only necessary to raise the valve l .l vso as, by admitting air to the chamber G, to l establish equilibrium between the pressure l therein and that ol' the atmosphere. l lt will be obvious that the gasketK, iril stead ol' being permanently attached to the Cil lcylinder L.

beck-plate C, might be attached to and conwith a central aperture in one of its plates, sttute a lip for the mouth of the air-pump and with an inwardly closing ila valve con- 5 trollingi the aperture, and a pac ing ring on the said plate concentric with `the aperture 15 l for the purpose Set forth.

JAMES PRITCHARD. HAROLD PRITCHARD Claims.

1. A pneumatic printing frame provided with an aperture in its back plate'7 im automatic air exhaust valve controlling the ipern ture, undpacking means encircling the aperture, and arranged to form an air tight closure between the plate and a pump'.

2. A pneunmtic printing frzune provided i' Vitnesses:

WlLLIAM E. DA1/IES. FRANK C. HYDE. 

